A very happy birthday to Prince George! The youngster celebrated his fifth birthday on Sunday - but instead of wondering where all the time has gone, we've put together his cutest milestone moments - from the moment Prince William and Kate introduced him to the world on the steps of the Lindo Wing to his very first day at school to his adorable fifth birthday portrait!
GALLERY: A look back at the three times Prince George has gone to watch Prince William at the polo
Aged just five, Prince George has had an amazing life; travelling with his family abroad to Australia and Canada on royal tours, being page boys at two high profile weddings - Pippa Middleton and James Matthews, and Prince Harry and Meghan Markle - and, of course, becoming a big brother to siblngs, Princess Charlotte and Prince Louis. Although we have yet to see George interact with baby Louis, he and Charlotte are great friends, and were spotted playing together while watching their dad play polo. Click through the photos to see the future King's adorable milestone moments...
First public appearance – July 2013
A day after his long-awaited arrival, Prince George made his first ever public appearance on 22 July 2013 at St Mary's Hospital in Paddington, London. The little boy – who had not been named yet – was introduced by his parents Prince William and Kate, who were also making their first outing as parents.
The newborn future King slept soundly through his public debut, but appeared to give his first royal wave from inside his white shawl.
"It's been emotional," said Kate. "Any parent will know what this feeling is like."
"We're still working on a name," added William, who joked that George had a "good pair of lungs on him, that's for sure".
First official portrait – August 2013
A month later George starred in his first official portrait, which, unlike royal tradition, was not taken by an official photographer but by Kate's father Michael Middleton. George again dozed peacefully in his mother's arms as the new family posed with cocker spaniel Lupo and golden retriever Tilly for photos at the Middletons' home in Berkshire.
His christening – October 2013
Aged three months, George made his second high-profile appearance as he was christened at the Chapel Royal, St James's Palace in London. The newborn was dressed in the replica Honiton lace gown worn by all royal babies, and looked adorable as he took centre stage at the ceremony.
It was the first time he was seen in public with his father, his grandfather Prince Charles and his great-grandmother the Queen.
First holiday abroad – January 2014
For his first holiday abroad at just six months old, the future King took a long-haul flight to the Caribbean island of Mustique. Kate was pictured carrying her little boy off the plane, shielding him from the sun with a stripy hat.
The mother-son duo were celebrating the birthday of Kate's mum Carole Middleton, on the island that the Middletons usually frequent for some winter sun. Prince William, meanwhile, remained in the UK where he was completing an agricultural course at Cambridge University.
First engagement – April 2014
George's first ever engagement took place during a royal tour – also his first – to New Zealand. At eight months old the tot melted hearts, attending a playdate with other babies of similar age at Government House in Wellington.
According to parent Grant Collinge, George was "bubbly, a little bit feisty too, but a very friendly baby". Grant added: "He owned the place. No one was going to stand in his way." During the royals' stay at the Governor-General's residence, William also warned his hosts: "I hope that George doesn't keep you up. He's at his most vocal at 3am, as you may have noticed."
First trip to the zoo – April 2014
It was during his trip to the other side of the world that George also made his first visit to the zoo. In Australia, now nine months old, the cherubic youngster met a bilby named after him at Taronga Zoo, Sydney. As he squealed with delight and reached out for the animal, his mum Kate said: "He's trying to grab his ear!"
"If he gets it he'll never let go," laughed William, fondly kissing the top of his son's head. George has developed a love for animals, and is often spotted feeding the animals and playing in the sandpit at Snettisham Park Farm, just down the road from the Cambridges' family home Anmer Hall.
First outing at the polo – June 2014
Prince William had just as much to celebrate at the polo in June 2014 as his son George. The second in line was marking his first Father's Day, while George was attending his first polo match as a spectator.
George was seen taking some of his first steps at 11 months old and – holding his mum's hands – attempting to kick a ball at the Cirencester charity event. The royal tot also showed off his crawling skills, making a dash across the grass to try and pick up a polo mallet.
First birthday – July 2014
Just in time for his first birthday, George thrilled his parents when he started to walk unaided. Members of the public were given a glimpse of his skills in his official first birthday portraits, which were taken at the Sensational Butterflies exhibition at the Natural History Museum in London.
George posed for one solo photo, and was joined by his doting parents in another. "He's quick on his feet," royal photographer John Stillwell said. "He was walking towards me – I was kneeling down to take the picture and he was on top of me as soon as he started walking. He was very quick. He looked really steady on his feet."
George has since enjoyed regular trips to the Natural History Museum. He is a big fan of its world-famous dinosaur exhibition although Kate has revealed he is often just as interested in the pigeons and insects outside.
First Christmas at Buckingham Palace – December 2014
As he was too young to celebrate Christmas at Buckingham Palace the year of his birth, George attended his first annual family lunch the following year in 2014, when he was one and a half years old.
His Royal Cuteness was spotted arriving at the palace in a car driven by his uncle Prince Harry, and clutching the children's book Dig Dig Digging.
Meeting his sister Charlotte – May 2015
It was his baby sister's big day when Princess Charlotte was introduced to the world in May 2015. But Prince George managed to share some of the spotlight as he made an appearance at the hospital, where he was due to meet his sister for the first time.
George arrived to waiting crowds outside the Lindo Wing of St Mary's Hospital – the same place where he made his first appearance almost two years before. As George sweetly waved to well-wishers, William kissed his son on the top of his head and said, "Good boy".
First portrait with Charlotte – June 2015
His brotherly love for his baby sister was clear to see in George and Charlotte's first official portraits together.
George gently cradled the tiny baby on a chair at home in Anmer Hall in beautiful photos taken by their doting mother Kate, a keen photographer. Once again the Duchess chose to step behind the camera to capture her daughter's first portraits, which were taken just weeks after the birth but not released until early June.
It was the first time George and Charlotte had been seen together.
First Trooping the Colour – June 2015
Now nearly two years old, George was old enough to make his debut on the Buckingham Palace balcony for the Queen's official birthday celebrations in June. In a blue romper suit worn by his father William for the same event more than 30 years earlier, George drew gasps of admiration from the crowds below.
The young royal had already stolen the show earlier, giggling and sticking out his tongue as he watched his family take part in the Trooping the Colour ceremony from a window, in the arms of his Spanish nanny Maria Turrion.
First official portrait of the Cambridges – December 2015
In the first official photograph of the Cambridges as a family of four, George looked full of fun, standing next to his mum while a proud William looked on.
The sweet picture was taken in late October as the leaves were falling in Kensington Palace, and served as the family's 2015 Christmas card. Now two and a half years old, with a better understanding of what Christmas is about, the festive season had George "bouncing around like a rabbit," said William.
First day at nursery – January 2016
The following year in January George set off for his first day at Westacre Montessori nursery school. He now attends twice a week while the family are in Norfolk, joining in with activities such as arts and crafts and playing with his young friends.
Kate once again acted as official photographer and documented George's milestone, capturing her firstborn in front of a colourful mural, all dressed up in his quilted coat and carrying his mini backpack.
First ski holiday – March 2016
For their first holiday as a family of four, the Cambridges enjoyed a short ski break to Courchevel in the French Alps. It was the first time that George and his younger sister Charlotte had their first taste of snow, and judging by the family's fun-filled official portraits, the children inherited their parents' love of skiing.
William had said previously that George got on "very well" with his sister. "No broken bones so far but they are trying – running around and pushing things and jumping," he laughed.
First time meeting a US President – April 2016
Shortly after, George once again stole the show as President Obama visited Kensington Palace. The young Prince, permitted to stay up late for the special occasion, was an adorable sight dressed in his pyjamas and personalised dressing gown. He looked a little overwhelmed as Barack knelt down to shake his hand.
First stamp – April 2016
George appeared on his first postage stamp as part of a set issued to mark Her Majesty's 90th birthday. In a heartwarming family portrait, he stood on a pile of foam blocks to raise him level with his great-grandmother the Queen, grandfather Charles and father William.
George and the other youngest members of the family, including Princess Charlotte, then appeared in another official birthday photograph taken by celebrity artist Annie Leibovitz at Windsor Castle.
First engagement in the UK – July 2016
A fortnight before his third birthday, George carried out his first engagement on home soil. The future King joined his parents on an official visit to the Royal International Air Tattoo at RAF Fairford in Gloucestershire.
An avid fan of anything with motors and wheels, George skipped around and jumped up and down with excitement as he inspected the aircraft with William and Kate. He was led up the ladder of one of the RAF Aerobatic Team's Red Arrow Hawks by helicopter pilot William, and even had the chance to sit in the cockpit.
"Mummy, can I fly the Red Arrow now?" he asked Kate, with William gently telling his son, "Not right now."
Page boy for the first time ever - May 2017
Prince George looked simply adorable in green trousers and a white smock shirt as he attended his aunt Pippa Middleton's wedding. Pippa tied the knot to James Matthews at St Mark's Church, and the Prince was a page boy, while his little sister was a bridesmaid.
Prince George begins school - September 2017
Prince George was all smiles while dressed up for his first day of school. Since his mum, Kate, was unfortunately suffering from severe morning sickness while pregnant with Prince Louis, George was taken to his first day by his dad, William, who smiled with him on the snap to mark his first day of education!
Visiting his baby brother in hospital - April 2018
Prince George might have been too young to remember visiting his baby sister, Charlotte, in hospital - but visiting Prince Louis might stick in his mind! The little royal looked pretty daunted by the crowds, and held tight to his dad's hand while letting his little sister, Charlotte, waves enthusiastically to the gathered crowd outside of the Lindo Wing.
Page boy at a royal wedding - May 2018
Prince George looked adorable a minature version of his uncle Harry's uniform as he took part in the royal wedding of the year along with fellow page boys, Jasper George Galloway Dyer and Brian and John Milroney. Meanwhile his little sister, Princess Charlotte, was a bridesmaid.